1. Field of the Invention
The present invention relates to a multi-phase coil terminal structure used with a multi-phase coil for use in a motor, and to a motor including the same.
2. Description of the Related Art
A motor is easy to control, and therefore has conventionally been used, as a driving source of a mechanical structure, in various equipments such as industrial instruments and household appliances. The more these various equipments become widespread, the more and more the improvement in the reliability of the equipments is demanded. Under the circumstance described above, it is a matter of course that the improvement in the reliability of a motor used in those equipments is also demanded.
For the purpose of improving the reliability, it may be needed that a short circuit is made between two common terminals in a uni-polar drive circuit in which electric current is caused to flow through a coil of a motor in one direction.
One method for making a short circuit is disclosed in Japanese Patent Application Laid-Open No. H02-294299. Referring to FIG. 15 herein, a plate-like conduction means (conduction member 130) is provided to connect between two terminals 126B and 128B, wherein the terminals 126B and 128B are inserted respectively in openings 130A and 130B of the conduction means (conduction member 130).
Also, another method for making a short circuit between common terminals is disclosed in Japanese Patent Application Laid-Open No. 2006-238617. Referring FIG. 16 herein, a terminal substrate (PC board) 250 is used to make a short circuit between common terminals Q2 and P2.
Further, still another method is disclosed in Japanese Patent Publication Laid-Open No. H09-308215. Referring to FIG. 17 herein, common terminals 325a and 326a are joined to each other for unification, and also it is conventionally known that an output terminal 325b is formed at the connection portion of the common terminals 325a and 326a. 
However, in the method described in Japanese Patent Application Laid-Open No. H02-294299, there is a problem that when the plate-like conduction means (conduction member 130) is attached to connect between the terminals 126B and 128B, soldered portions of the terminals 126B and 128B are scratched by edges of the openings 130A and 130B thus causing rust, which results in difficulty to assure a long term reliability.
Also, there is another problem about reliability found in the above method that since the plate-like conduction means (conduction member 130) is exposed, if starting/finishing wire ends of windings wrapped around other terminals 128A, 128C, 126A and 126C stick out, then an unintended short circuit may be caused between the plate-like means (conduction member 130) and the other terminals 128A, 128C, 126A and 126C. Further, an assembly process of attaching the plate-like conduction means between the terminals 126B and 128B is additionally required thus causing a cost increase problem.
In the method described in Japanese Patent Application Laid-Open No. 2006-238617, the component cost for the terminal substrate 250 is required, and also a cost increase occurs due to requirement of an assembly process, a soldering process and a solder material cost. And, there are concerns about reliability inherent in soldering work (poor soldering, negligence to solder, solder bridge, and the like).
In the method described in Japanese Patent Publication Laid-Open No. H09-308215, for the reason of design requirement of a device to be connected, two common terminals 325a and 326a are joined to each other and unified into one output terminal. This method is superior to the above described two methods in terms of cost and reliability, but since a directional property (orientation) is predefined in the terminal arrangement, caution and check are required in order to avoid making a mistake with respect to the direction or orientation during work processes of winding, coil terminal treatment, motor assembly and the like, which lowers operating efficiency and which eventually results in inviting a cost increase. Also, since this method carries a risk of making a mistake with respect to the direction or orientation, there exists a reliability problem, too.